Going underground for optimal crops and yields

Researchers from the University of Nottingham in the United Kingdom have designed an innovative technique to study the underground world of plants. Presented in the journal Plant Physiology, the results of this study will lead to improved breeding techniques for crop varieties, as well as better yields.

The novel approach is based on the same X-ray technology used in hospital computed tomography (CT) scans. It integrates new image analysis software that can automatically distinguish the roots of plants from other soil-based materials.

The researchers, from the Centre for Plant Integrative Biology (CPIB), tested this approach on the roots of maize, wheat and tomato. They studied the architecture, what experts refer to as the shape and branching pattern, of roots in soil by using X-ray micro computed tomography (micro CT). The team then entered the information into the new RooTrak software, which enabled them to differentiate between roots and other soil elements.

'This technique is a hugely important advance,' says Dr Sacha Mooney, an expert in soil physics in the School of Biosciences. 'The application of X-ray CT for visualising roots has been limited because we simply couldn't see a large portion of the root structure. RooTrak has enabled us to overcome this and has opened up the use of the technology for exploring the key questions regarding how we can manipulate plants and soils for improving our food security.'

The innovative software works by obtaining a stack of virtual slices through the root-bearing soil. According to the researchers, RooTrak treats each slice as a movie frame. The slice's static roots are treated as moving objects that can be tracked. So the software can tell the difference between root and water or organic elements in the soil, doing away with any glitches resulting from other techniques. This latest technique offers a three-dimensional (3D) detailed and accurate root architecture.

'Thinking of micro CT data as a sequence of images allows us to solve the problems caused by variations in the appearance of plant roots and the similarity of some roots to the surrounding soil,' says Tony Pridmore, head of data at CPIB and an expert in tracking and analysis software. 'This is important because we can now extract descriptions of root architecture quickly and objectively.'

Adds CPIB's Professor Malcolm Bennet, an expert in root biology: 'Root architecture critically influences nutrient and water uptake. A key impediment to genetic analysis of root architecture in crops grown in soil has been the ability to image live roots. Recent advances in micro CT and RooTrak software at Nottingham now make this possible.'

The Nottingham team has clinched a European Research Council (ERC) Advanced Investigator Grant worth EUR 3.5 million under the EU's Seventh Framework Programme (FP7). They will use this software along with an innovative micro CT–based imaging approach to image the roots of wheat, and choose new varieties with optimal water and nutrient uptake efficiencies.

The CPIB will lead this new project, supported by experts from Australia, Europe and Mexico.